Joints for concrete slabs, and joint supports

ABSTRACT

A prefabricated expansion joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having an enlarged base portion for connecting directly or indirectly to a surface on which a concrete slab is to be made, a top portion for coming flush with the surface of the concrete slab that is to be made, and an intermediate portion with two side walls extending between the base portion and the top portion. The top portion comprises a strip of flexible plastics material in which there extends a central web of relatively rigid plastics material connected via its bottom edge to the side walls of the joint, forming a single part together therewith and extending vertically over at least the major fraction of the height of the top portion of the joint.

BACKGROUND OF THE INVENTION

The invention relates to making expansion or bay joints for concrete slabs, and more particularly to hollow bars or sections of plastics material for constituting such joints and to accessories enabling them to be put into place on a surface on which a concrete slab is to be cast.

Hollow plastics material sections that are put into place on a surface prior to casting a slab and that subsequently remain permanently therein so as to constitute joints are well known. Such sections also be used for making it easier to level the slab while it is being formed, by placing the sections at a height that corresponds to the thickness desired for the slab. Reference can be made to patent documents FR 2 292 907, EP 0 053 977, and EP 0 152 367.

At their tops, those prior art sections present a narrow width, and as a result gaps can form in the surface of the slab between the joint and the two adjacent portions of the slab, due to the dimensions of the concrete varying. In addition to this causing the joint to take on an appearance that can be unattractive, the presence of such a gap or clearance facilitates the insertion or penetration of water or other liquids or solids.

In addition, in order to put sections into place and adjust their height and their horizontal level, their bases are secured by means of mortar dots on the surface on which a slab is to be cast, or they are placed on supports which are themselves secured by such mortar dots. That operation is time consuming and must be performed long enough in advance to allow the mortar to set before the slab is cast.

OBJECT AND SUMMARY OF THE INVENTION

The invention seeks to remedy those drawbacks and for this purpose, in a first aspect, it provides a prefabricated joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having an enlarged base portion for connecting directly or indirectly to a surface on which a concrete slab is to be made, a top portion that is to be flush with the surface of the concrete slab that is to be made, and an intermediate portion with two side walls extending between the base portion and the top portion, in which the top portion comprises a strip of flexible plastics material into which there extends a central web of relatively rigid plastics material connected via its bottom edge to the side walls of the joint being formed integrally therewith and extending vertically over at least the major fraction of the height of the top portion of the joint.

Thus, the presence of a strip of flexible plastics material at the top of the joint makes it possible to guarantee that sealing is maintained between the joint and the adjacent portions of the slab while nevertheless conserving sufficient mechanical strength by virtue of the relatively rigid central web.

Advantageously, the strip of flexible plastics material is coextruded with the remainder of the joint that is made of a relatively rigid plastics material, thereby enabling the joint to be manufactured in a single operation.

Also advantageously, the web of the top portion has a top edge that is set back from the top face of the strip of flexible plastics material. Thus, the top edge of the joint that becomes flush with the surface of the slab, presents a uniform surface state giving the slab a generally clean appearance. In addition, this gives the top of the joint a certain amount of flexibility in the vertical direction.

In a variant embodiment, the strip of flexible plastics material has free outer side surfaces that are situated substantially extending the side walls of the joint. The strip of flexible plastics material then comes directly into contact with the concrete of the slab on either side of the joint. The strip of flexible plastics material then preferably presents fluting or similar portions in relief on its outer side faces to enable it to bond well with the concrete.

In another variant embodiment, the strip of flexible plastics material is disposed between two side walls of relatively rigid plastics material each extending over at least a fraction of the height of the top portion, in register with the side walls of the joint, thereby reinforcing the sides of the top of the joint. The side walls on either side of the strip of flexible plastics material preferably present splines or external portions in relief serving to provide good bonding with the concrete.

The side walls of the joint are advantageously provided with splines for bonding them with the concrete of the slab, in conventional manner. It is also possible to provide the side walls with wings that constitute water-stopping means.

In another of its aspects, the invention also provides a support for a prefabricated joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having a base portion, a top portion for coming flush with the top surface of a concrete slab to be made, and an intermediate portion with two side walls connecting the base portion to the top portion, the support comprising:

a cradle having a portion substantially of channel-section in which a portion of the base of a joint can be engaged, and a sleeve secured to the substantially channel-section portion; and

a stand carrying the cradle, the stand having a rod with one end supported by legs for securing the stand on a surface on which a slab is to be made, and the sleeve of the cradle engaging on the rod with it being possible to adjust the position of the cradle along the rod.

The sleeve may be screwed onto the rod, which should then be threaded. Advantageously, the rod is hollow and presents openings or slots through its wall. The rod can then become filled with concrete grout while the slab is being cast.

The cradle may comprise two substantially channel-section portions both secured to the sleeve and in which it is possible to engage base portions of joints of different dimensions.

The stand may include at least one leg with a hollow sleeve for passing a rod or nail for fastening it to the surface.

In order to enable it to be fastened to a shuttering floor slab, the stand may also have at least one leg with a housing for receiving a metal reinforcing rod of the shuttering preslab that projects from the surface thereof.

In another of its aspects, the invention also provides a support for a prefabricated joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having a base portion, a top portion for coming flush with the top surface of a concrete slab to be made, and an intermediate portion with two side walls connecting the base portion to the top portion, the support comprising:

a cradle having a substantially channel-section portion in which a base portion of a joint can be engaged and a sleeve secured to the substantially channel-section portion, the sleeve engaging on a rod or spike engaged in the surface.

The vertical position of the cradle, and thus of the joint, can then be adjusted by pushing in the rod or the leg.

In a variant, the sleeve is screwed onto a bushing suitable for engaging on a rod or a spike engaged in the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood on reading the following description given by way of non-limiting indication with reference to the accompanying drawings, in which:

FIG. 1 is an elevation view in cross-section of an embodiment of a joint in a first aspect of the invention;

FIG. 2 is a cross-section view of a variant embodiment of the FIG. 1 joint;

FIG. 3 is a cross-section view of the top portion of the FIG. 1 joint showing another variant embodiment;

FIG. 4 is a cross-section view showing another variant embodiment;

FIG. 5 is a perspective view of an embodiment of a joint support for a concrete slab in another aspect of the invention;

FIG. 6 is an elevation view in section showing an assembly constituted by a joint and the FIG. 5 support;

FIG. 7 is a perspective view showing a first variant embodiment of the cradle of the FIG. 5 support;

FIG. 8 is a perspective view showing a second variant embodiment of the cradle of the FIG. 5 support;

FIG. 9 is a perspective view of an embodiment of a joint support for a concrete slab in yet another aspect of the invention ;

FIG. 10 is a cross-section view on plane X-X of FIG. 9 showing the stand of the FIG. 3 joint support;

FIG. 11 is an elevation view in section on plane XI-XI of FIG. 10 showing an assembly constituted by an expansion joint and the support of FIG. 9; and

FIG. 12 is a section view showing a variant embodiment of the joint support of FIGS. 9 to 11.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 shows an expansion or bay joint 100 for a concrete slab in a first aspect of the invention.

The joint ruler or joint 100 is a plastics material extrusion having a base portion 110 forming a hollow sole, a top portion 150, and a hollow intermediate portion 130 interconnecting the base and top portions.

The base portion 110 is of greater width and comprises a central portion 112 extending the intermediate portion 130, and two flanges 120 and 122 situated on either side of the central portion. The base portion 110 presents a bottom wall constituting the bottom face of the joint 100 and comprising a portion 112 a forming the bottom wall of the central portion 112, and two portions 120 a and 122 a forming the bottom walls of the flanges 120 and 122. The wall portions 120 a, 122 a are connected to the wall portion 112 a and extend away therefrom in directions that slope downwards a little to the ends of the flanges 120, 122. The inside volume of the central portion 112 is defined by the wall portion 112 a, two lateral partitions 114 a, 114 b, and a transverse top partition 116 interconnecting the lateral partition. The inside volumes of the flanges 120, 122 are defined by the wall portions 120 a, 122 a, end longitudinal edges 120 b, 122 b of the flanges, top walls 120 c, 122 c of the flanges, and the lateral partitions 114 a, 114 b. The flanges 120, 122 are of height that decreases going towards their longitudinal edges 120 b, 122 b, the walls 120 c, 122 c sloping downwards from where they join the central portion 112.

The hollow intermediate portion 130 presents two side walls 132 a, 132 b connecting the central portion 112 of the base 110 to the top 150. The inside volume of the intermediate portion 130 is defined by the walls 132 a, 132 b, the partition 116, and a top wall 134. Spacer-forming internal transverse partitions 136 a, 136 b interconnect the walls 132 a, 132 b. The intermediate portion 130 is of width that decreases going away from the base 110, the walls 132 a, 132 b sloping towards each other going towards the top wall 134. It should be observed that the partitions 114 a, 114 b extend in register with the walls 132 a, 132 b, and that the top walls 120 c, 122 c of the flanges 120, 122 meet the walls 132 a, 132 b substantially level with the partition 116. The walls 132 a, 132 b are at obtuse angles relative to the walls 120 c, 122 c. The walls 132 a, 132 b carry splines 138 a, 138 b presenting flared ends, e.g. being of Y-shaped section so as to be capable of becoming anchored in the concrete cast on either side of the joint 100.

The top portion 150 comprises a strip 152 of flexible material, of substantially rectangular section, of a width that corresponds substantially to the width of the top wall 134 of the intermediate portion, and surmounting it. A central web 154 in the form of a vertical tongue is embedded in the strip 152. The web 154 is connected to the outside surface of the top wall 134 of the intermediate portion, substantially in the middle of said wall 134. It should be observed that the central web extends over a major fraction of the height of the strip 152, but preferably does not extend over its full height so that the terminal portion of the top 150 is constituted solely by the flexible material of the strip 152. The outside surfaces of the strip 152 present fluting 156 or other similar portions in relief extending longitudinally while presenting a profile that slopes relative to the horizontal for bonding with the concrete that is to be cast on either side of the joint.

With the exception of the strip 152, the joint 100 is made of a plastics material that is relatively rigid, e.g. rigid polyvinylchloride (PVC).

The strip 152 is made of a flexible plastics material that is elastically deformable, e.g. flexible PVC. The joint 100 is advantageously made as a single piece by coextruding the strip 152 with the remainder of the joint, thus ensuring that the strip 152 is bonded to the remainder of the joint.

The joint 100 is put into place on a surface on which a concrete slab is to be formed in such a manner that the top surface of the top portion 150 is substantially at the same level as the top surface of the concrete slab that is to be formed. Naturally, as many joints as are needed are put into place, and on each occasion over the desired length.

Liquid concrete is cast on either side of the joint 100 up to the top thereof. The joint 100 may then advantageously be used as a guide for a screed for leveling the slab, in particular a vibrating screed that also serves to compact the concrete. While the screed is passing over it, the strip 152 can be compressed because of the flexibility of the material from which it is made, and because of its capacity for elastic deformation, it subsequently returns to its original position, thus providing a clean appearance to the top surface of the joint.

The web 154 embedded in the strip 152 is made integrally with the portions 130 and 110 and serves to hold the top 150 of the joint straight and to limit compression of the strip 152.

While the concrete is solidifying, the splines 138 a, 138 b become anchored in the concrete so that the walls 132 a, 132 b follow the contraction and expansion movements of the concrete, the joint 100 remaining permanently in the slab of concrete that is formed. In spite of the relatively rigid nature of the material constituting the portions 110 and 130, they remain intact because they are hollow. In order to encourage lateral deformation, the spacer-forming partitions 116, 136 a, 136 b present a V-shaped section of obtuse angle that advantageously decreases with decreasing width of the joint. At the top 150, the flexible nature of the material of the strip 152 enables the top of the joint to follow dimensional variations of the concrete, the fluting 156 formed on the side faces 152 a, 152 b enhancing bonding with the concrete.

Nevertheless, in the event of the concrete shrinking considerably, a gap can appear between the joint 100 and the concrete of the slab. The walls 132 a, 132 b may be provided with longitudinally-extending wings 140 a, 140 b that project from the outside surfaces of the walls 132 a, 132 b in a direction that is horizontal or that slopes upwards a little, as shown in FIG. 2. The wings 140 a, 140 b constitute water-stopping means preventing water from infiltrating if a gap is present at the surface of the slab between the joint 100 and the concrete.

In the embodiment of FIG. 1, the strip 152 of the top portion of the joint 100 has side surfaces that are free. In a variant they may be provided with side cheeks or walls 156 a, 156 b made of relatively rigid plastics material, e.g. out of the same material as the portions 130 and 150 of the joint, and preferably coextruded with the remainder of the joint, as shown in FIG. 3. The cheeks 156 a, 156 b contribute to holding the top of the joint. Like the web 154, they preferably extend over a major fraction of the height of the strip 152, but not over its entire height, thus ensuring that the strip 152 can be compressed vertically. The cheeks 158 a, 158 b may be flush with the top surface of the joint 100 as shown in FIG. 3, or they may be connected to the walls 132 a and 132 b at the top ends thereof. The outside surfaces of the cheeks 158 a, 158 b present longitudinally-extending splines 159 or other similar portions in relief that extend longitudinally and that present a profile that slopes relative to the horizontal so as to bond with the concrete cast on either side of the joint.

In order to be put into place on a surface where a concrete slab is to be formed, the joint 100 may be placed on supports that are adjustable in height, such as at the supports described below. Nevertheless, it is possible to envisage securing the joint to a dot of mortar. Under such circumstances, and as shown in FIG. 4, the bottom wall of the joint may be provided with legs 126 in the form of longitudinally-extending splines that are connected to the outside surfaces of the walls 112 a, 120 a, and 122 a. The legs 126 serve to anchor the joint. The legs connected to the flanges 120, 122 may be extended inside the flanges by stiffening spacers 120 d, 122 d. It is also possible to give the wall 112 a a V-shaped section with its tip connected to a leg 126.

FIG. 5 shows a support 200 constituting another aspect of the invention and suitable for use in particular with a joint such as the joint 100 of FIG. 1.

The support 200 comprises a cradle 202 carried by a stand 210. The cradle 202 presents a portion 204 in the form of a channel-section slideway adapted to receive the base portion of a joint. The portion 204 is reinforced by a bracket 206 on its underside and is secured to a sleeve 208 engaged on a threaded hollow rod 212 that forms a part of the stand 210. The sleeve 208 is tapped so as to enable it to be engaged on the rod 212 and be moved in translation therealong by screw engagement. Slots or openings 212 a are formed through the wall of the rod 212. Thus, while concrete is being cast, concrete gout can penetrate into the rod 212 and fill it, thus enabling the rod to withstand the pressure of the concrete.

At its bottom end, the rod 212 is engaged in a socket comprising a sleeve 213 secured to a plurality of legs 214, 216.

The bottom portion 212 b of the rod 212 is engaged without clearance in the sleeve, the wall thereof possibly presenting splines against which the bottom portion 212 b of the rod 212 comes into contact. The engagement of the rod 212 in the sleeve 213 is limited by a step 212 c in the rod 212 coming into abutment on the sleeve 213.

At their ends, the legs 214, e.g. two diametrically opposite legs, are secured to sleeves 214 a enabling the support 200 to be secured to a surface by nails engaged in the sleeves. At their second ends, the legs 216, e.g. two diametrically opposite legs, carry housings 216 a in which it is possible to engage rods or reinforcing strips belonging to a preslab shuttering on which a concrete slab is to be formed, the rods or strips projecting form the surface of the shuttering slab. Projecting portions 218 or studs or steps 219 may be formed at the ends of the legs 214, 216, and/or on top of them in order to retain the rods of metal reinforcement for the slab that is to be made and prevent any sliding of these rods.

After the stand has been secured in place, the position of the cradle 202 along the rod 212 is adjusted by screwing the sleeve 208 on the rod 212 so as to bring the joint supported by the cradle to the desired height, with the orientation of the cradle being adjustable by turning the rod 212 in the housing defined by the sleeve 213.

The support 200 may be made of plastics material by molding three parts: the cradle 202, the rod 212, and the unit constituted by the sleeve 213 and the legs 214, 216.

FIG. 6 shows a support 200 with the base 110 of a joint 100 engaged on the cradle 202.

FIG. 7 shows a variant embodiment of the cradle 202 comprising two portions 204 and 204′ both in the form of channel-section slideways secured to the sleeve 208, e.g. in opposite positions. The portions 204 and 204′ are of different dimensions enabling the joint support to be used with joints having bases of two different widths.

FIG. 8 shows another variant embodiment of a cradle 202 that differs from the cradle shown in FIG. 7 in that it further comprises fins 207 having horizontal top surfaces that are secured to the sleeve 208 at its top end. By way of example, there are two fins 207 that are angularly offset from the channel-section portion 204 and 204′ so as to avoid interfering with joints engaged thereon. The fins 207 enable the cradle 202 and the stand on which it is mounted to be used not only as a joint support, but also as a marker for leveling a concrete slab by adjusting the position of the sleeve 208 so that the top edges of the fins 207 are situated at the desired level from the top surface of the slab. The rod on which the sleeve 208 is screwed may be cut so that it does not project beyond the top edges of the fins.

It should also be observed that the stand 210 could be provided with legs that are all identical, and that the number of legs could be other than four.

FIGS. 9 and 10 show a support 300 in yet another aspect of the invention, suitable for use in particular with a joint such as the joint 100 shown in FIG. 1.

The support 300 comprises a cradle 302 having a portion 304 in the form of a channel-section slideway adapted to receive the base portion of a joint, and a hollow sleeve 306 which is connected to the bottom surface of the portion 304 substantially in the middle thereof, the portion 304 and the sleeve 306 forming a single part. The inside wall of the sleeve 306 is provided with splines 308 formed integrally with the sleeve 306 and having tips that define a central passage whereby the sleeve 306 can be engaged on a spike or rod 310 engaged in a surface on which a concrete slab is to be formed. The top end of the spike 310 bears against the bottom surface of the portion 304 of the cradle 302 whose vertical position is adjusted for the degree to which the spike or rod 310 is engaged.

The cradle 302 may be made as a single part by molding a plastics material.

FIG. 11 shows a support 300 with the base 110 of a joint 100 engaged on the cradle 302. The splines 308 are capable of compensating a small amount of misalignment between the axis of the sleeve 306 and the axis of the spike 310 when the spike is engaged in a manner that is not exactly vertical.

FIG. 12 shows a variant embodiment of the support of FIGS. 9 to 11 in which the cradle 302 presents a hollow sleeve 306′ having an inside thread so as to enable it to be screwed onto a threaded bushing 307 slidably engaged on the spike or rod 310. At its top end, the bushing 307 presents a step in its inside face enabling it to be pressed against the top end of the spike or rod 310. It is thus possible to adjust the vertical position of the cradle 302 by turning the sleeve 306′, with it being possible to adjust the orientation of the cradle by turning the bushing 307 on the spike or rod 310.

Although the supports 200 and 300 are described as being used with a joint such as the joint 100 of FIG. 1, it is also possible to use the supports with other types of hollow joint having a base portion, a top portion, and an intermediate portion with two side walls connecting the base portion to the top portion, in particular prior art joints that are not necessarily provided with a strip of flexible material at their tops. 

1. A prefabricated joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having an enlarged base portion for connecting directly or indirectly to a surface on which a concrete slab is to be made, a top portion that is to be flush with the surface of the concrete slab that is to be made, and an intermediate portion with two side walls extending between the base portion and the top portion, in which the top portion comprises a strip of flexible plastics material into which there extends a central web of relatively rigid plastics material connected via its bottom edge to the side walls of the joint being formed integrally therewith and extending vertically over at least the major fraction of the height of the top portion of the joint.
 2. A joint according to claim 1, in which the strip of flexible plastics material is coextruded with the remainder of the joint made of relatively rigid plastics material.
 3. A joint according to claim 1, in which the web of the top portion has a top edge that is set back from the top face of the strip of flexible plastics material.
 4. A joint according to claim 1, in which the strip of flexible plastics material has free outside surfaces situated substantially extending the side walls of the joint.
 5. A joint according to claim 4, in which the strip of flexible material presents fluting on its outer side faces.
 6. A joint according to claim 1, in which the strip of flexible plastics material is disposed between two side walls of relatively rigid plastics material extending over at least a fraction of the height of the top portion, in register with the side walls of the joint.
 7. A joint according to claim 6, in which the side walls on either side of the strip of flexible plastics material presents external splines.
 8. A joint according to claim 1, in which the side walls of the intermediate portion of the joint present wings forming water-stopping means.
 9. A support for a prefabricated joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having a base portion, a top portion for coming flush with the top surface of a concrete slab to be made, and an intermediate portion with two side walls connecting the base portion to the top portion, in which the support comprises: a cradle having a portion substantially of channel-section in which a portion of the base of a joint can be engaged, and a sleeve secured to the substantially channel-section portion; and a stand carrying the cradle, the stand having a rod with one end supported by legs for securing the stand on a surface on which a slab is to be made, and the sleeve of the cradle engaging on the rod with it being possible to adjust the position of the cradle along the rod.
 10. A support according to claim 9, in which the sleeve is engaged on the rod by screw-fastening.
 11. A support according to claim 9, in which the rod is hollow and presents openings through its wall.
 12. A support according to claim 9, in which the cradle comprises two substantially channel-section portions secured to the sleeve and suitable for having engaged therein the base portions of joints of different dimensions.
 13. A support according to claim 9, in which the stand has at least one leg with a hollow sleeve for passing a rod or nail for fastening the stand to the surface.
 14. A support according to claim 9, for fastening on a concrete shuttering floor slab in which the stand has at least one leg with a housing for passing a metal reinforcing rod of the shuttering slab and projecting from the surface thereof.
 15. A support for a prefabricated joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having a base portion, a top portion for coming flush with the top surface of a concrete slab to be made, and an intermediate portion with two side walls connecting the base portion to the top portion, in which the support comprises: a cradle having a substantially channel-section portion in which a base portion of a joint can be engaged and a sleeve secured to the substantially channel-section portion, the sleeve being suitable for engaging on a rod or spike engaged in the surface.
 16. A support according to claim 15, in which the sleeve is screwed onto a bushing suitable for engaging on a rod or spike engaged in the surface.
 17. An assembly formed by at least one prefabricated expansion joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having a base portion, a top portion for coming flush with the top surface of a slab of concrete to be made, and an intermediate portion with two side walls interconnecting the base portion and the top portion, and at least one support having a cradle with a substantially channel-section portion in which the base portion of the joint can be engaged and having a sleeve secured to the substantially channel-section portion, and a stand carrying the cradle, the stand comprising a rod with one end secured to legs for fastening the stand on a surface on which a slab is to be made, the sleeve of the cradle engaging on the rod with it being possible to adjust the position of the cradle along the rod.
 18. An assembly according to claim 17, in which the top portion of the joint comprises a strip of flexible plastics material in which there extends a central web of relatively rigid plastics material connected via its bottom edge to the side walls of the joint, forming a single part therewith and extending vertically over at least the major fraction of the height of the top portion of the joint.
 19. An assembly formed by at least one prefabricated expansion joint for a concrete slab, the joint comprising a hollow extrusion of plastics material having a base portion, a top portion for coming flush with the top surface of a slab of concrete to be made, and an intermediate portion with two side walls interconnecting the base portion and the top portion, and at least one support having a cradle with a substantially channel-section portion in which the base portion of the joint can be engaged and having a sleeve secured to the substantially channel-section portion, the sleeve engaging on a rod or a spike engaged in the surface.
 20. An assembly according to claim 19, in which the top portion of the joint comprises a strip of flexible plastics material in which there extends a central web of relatively rigid plastics material connected via its bottom edge to the side walls of the joint, forming a single part therewith and extending vertically over at least the major fraction of the height of the top portion of the joint. 